ETM+数据绝对反射率反演方法分析

Evaluation of Simplified Procedures for Retrieval of Absolute Surface Reflectance from Landsat Enhanced Thematic Mapper (ETM+)

将传感器原始记录信号反演为地面反射率对于遥感定量化应用非常重要。为了寻找一种简单、精度高的绝对反射率反演方法 ,本文以新疆哈密为试验区 ,使用经验线方法和基于模拟大气状况的辐射传输模型方法对 1 999年 8月的ETM +数据进行了反演研究。通过将各反演方法得到的反射率值与地面实测值及星上反射率进行对比来验证反演效果 ,发现经验线方法精度最高 ,中误差仅为 0 .0 6 3,而基于模拟大气状况的辐射传输模型方法精度差 ,甚至不如未经大气校正的数据。这是由于星上定标系数误差、辐射传输方程自身误差以及模拟大气误差综合的结果 。

To collect remotely sensed data of lasting quantitative value, it is necessary to calibrate them to physical units such as reflectance. Optical remotely sensed data are affected by sensor characteristics, illumination geometry and atmospheric conditions. In order to fully realize the potential of satellite spectral data for earth-monitoring applications, it is to convert sensor output to values independent of atmospheric conditions. In response to the need for a simple atmospheric correction method and the consequent verification of such a method, an experiment was conducted in Hami, Xinjiang, to acquire a data set suitable for testing atmospheric correction procedures. Two procedures, including radiative transfer model (RTM) with simulated atmospheres and the empirical line method were evaluated by comparing surface reflectance factors derived from Landsat ETM data with ground-based reflectance. Simultaneously the uncorrected or “apparent” surface reflectance factors were computed using the absolute radiometric calibration coefficients of the TM in order to compare to the other two procedures to show their correction results. Of the three, the empirical line provided good results. The RMS error of satellite-based reflectance factors was only 0.063 reflectance. The RTM with simulated atmospheres produced greater error than the empirical line method, even than the uncorrected data.